We are bombarded with messages telling us that breakfast is ‘the most important meal of the day’ and that eating every 3 hours will ‘speed up your metabolism’. So fasting and skipping meals MUST wreak havoc on your metabolism and cause weight gain. Right? Well, think again.
Intermittent fasting (IF) has recently gained popularity as new research studies and diet trends emerge. Fasting has been practiced for centuries (i.e. for religious regions) but is there a benefit to IF? And specifically time-restricted feeding (consuming energy intake within a specific time window each day)?
The short answer: Yes.
Keep in mind there are currently only two trials in human beings that look at time-restricted feeding interventions, so more research is warranted. With that said, the results are promising. Both of the trials found significant reduction in weight, while one study even saw reductions in fasting blood glucose and improvements in LDL and HDL cholesterol levels.
Key takeaways from the current research:
- The fasting occurred daily for at least 11 hours between 7 pm and 6 am in one study and was given as 1 meal (with comparison group eating 3 square meals) in another study. So although recent diet trends recommend a 16-hour fast with 8 hours of eating, there is still inadequate data to determine the ideal fasting period.
- Research in animals shows that IF not only reduces obesity but also reduces chronic diseases such as diabetes and cancer and conditions such as nonalcoholic fatty liver disease.
- Opponents of IF state that periods of fasting lead to periods of overeating, however this is not clear and has not been proven.
- Data is lacking regarding the effects of IF on other health behaviors such as diet quality, sleep, and physical activity – important factors in overall health.
So should you try intermittent fasting?
While this summary discusses intermittent fasting as a promising approach for weight loss and metabolic health, as a Registered Dietitian Nutritionist, I wouldn’t recommend it to everyone. People who are underweight, have a history of eating disorders, people with diabetes (or problems with blood sugar control), people with any medical condition, and people taking medications should never fast without consulting with a doctor first. Also, IF does seem to be more of a trend, than a sustainable way of eating. And the best eating pattern will always be one that you can create a lifestyle around and that you enjoy. If you’re reading this information and aren’t sure how this fits into your lifestyle, I would recommend working with a dietitian to create a successful nutrition plan tailored to YOU.
My recommendations are to either postpone your first 1-2 meals and eat your first meal around 11:00 am or Noon OR eat at your normal meal times in the morning and stop eating earlier in the evening (i.e. 5 pm). Try it for a day and if it’s not for you, STOP!!! If you are hungry, losing energy, not as alert, go back to your balanced healthy diet. There is no long-term research done on IF and I don’t think it is as ‘magical’ as some think. Most people who are interested in this way of eating are already consuming a minimally processed diet and probably already understand nutrition principles like macronutrients. I truly feel IF is best for males (i.e. they have different hormones than females) or those who are working to get VERY lean for a show or competition and eating in a window of time can help with cravings.
What are your thoughts on Intermittent Fasting?